Method of installing well points



June 4, 1968 H. scHNABEl., JR

METHOD OF NSTALLING WELL POINTS 2 Sheets-Sheet 1 Filed Jan. 3, 1966 n mw.kil n M W L, k, my.

`lune 4, 1968 Filed Jan. 3, 1966 METHOD OF NSTALLING WELL POINTS H.SCHNABEL., JR 3,386,510

2 Sheets-Sheet 2 Harry Schnabel Jr.

A QRNEYS INVENTOR United States Patent O 3,386,510 METHOD F INSTALLINGWELL POINTS Harry Schnabel, Jr., 5210 River Road, Bethesda, Md. 20616Filed' Jan. 3, 1966, Ser. No. 518,430 12 Claims. (Cl. 16S-34) ABSTRACT0F THE DISCLOSURE There is disclosed a -method of installing a wellpoint system in which each well point pipe has a continuous and uniformnoncircular cross section, by drilling each noncircular pipe into theground while simultaneously jetting water through the pipe. There ispositioned in closely fitting relation with the pipe strainer a sleeve,insoluble in cold water but highly soluble in hot water, which sleeve isremoved by passing hot water through the well point after it has beeninstalled.

This invention relates to an improved method for quickly andinexpensively installing well points.

Well point systems are widely used to exhaust or drain water from aselected ground area to lower the water table in the area. Such systemshave found particular application in various excavation projects such asthe construction of building foundations, sewers, tunnels, bridges,pumping stations and the like. The well point system is employed to keepwater out of the excavation while work proceeds.

Certain problems have arisen in connection with the installation ofheretofore known well point systems. Well points are generally installedby forcing the well point pipes into the ground and leaving them there.Considerable ditliculty is often experienced in installing the pipes ingravel or other hard soil. Although Imany different expedients have beendevised in attempts to meet this difficulty, they have beencharacterized by certain undesirable features. For example, some systemsemploy well point pipes which can only Ibe driven through the ground andcannot be used for jetting holes to receive themselves. Other systems,perhaps in the widest usage, employ well point pipes which can be jettedinto the ground but cannot be driven. Most of these systems em ploycomplex and expensive valve arrangements to permit jetting through thebottom of the pipe during installation but prevent axial inflow ofground water into the end of the pipe. Still other systems employ wellpoint pipes which can be driven and/or jetted but cannot be drilled intothe ground.

One aspect of the present invention provides a very simple well pointsystem which is capable of being installed through a simultaneouscombination of jetting, driving, and drilling. In this way, the systemmay be effectively and economically installed in most types of soil.Heretofore known systems have employed well point pipes having acircular cross section. Thus, the pipe must be tightly gripped by achuck or other means in a rotary table in order to apply the necessaryforce to rotate the pipe. It is difiicult to tightly grip the pipe insuch a manner and still permit it to slide through the rotary table andbe driven into the ground. Moreover, such tight gripping tends to cut ormar the surface of the pipe and create weak points. Thus a major problemin the installation of Patented June 4, 1968 ICC well point pipes hasbeen to apply a rotative force to the pipes while simultaneouslypermitting them to be driven into the ground. In accordance with oneaspect of this invention a noncircular, preferably square, well point isused to prevent slippage in the grip of the rotary table.

Well points conventionally have multiple perforations through the lowerperipheral wall to provide a strainer inlet for ground water which inletexcludes earth, rocks and other large solid objects. During the jettingoperation, these perforations permit the jetting water to emerge throughthe side of the pipe as well as through the bottom thereby reducing theeffectiveness of the jet.

Further, during the sinking of the Well point, the perforations may beclogged. Such clogging is a particular problem where a noncircular pipeis drilled into the ground.

To overcome the disadvantages of the prior art, it is an object of thepresent invention to provide an improved method for effectively andeconomically installing well point systems.

Another object of the invention is to provide such a method capable ofutilizing the simultaneous, combined actions of drilling, driving andjetting.

Still another object of the invention is to provide such a method inwhich the strainer openings through the wall of the well point aresealed during the installation and quickly and easily opened afterinstallation.

In general, one aspect of the invention relates to a method ofinstalling a well point system which comprises providing a plurality ofwell point pipes of uniform, noncircular cross section, said pipeshaving open bottoms with side openings near said bottoms, sinking saidpipes to a desired depth into the ground at spaced locations bysimultaneously slidingly and drivingly engaging each of the pipes in arotary drilling table having a noncircular pipe receiving opening toreceive the pipe in driving relation and rotating the rotary table,applying a downward force to each of the pipes, and jetting waterdownwardly through each of the pipes while it is being rotated,thereafter obstructing said open bottoms below said side openingsagainst the admission of earth, connecting a header to each of theinstalled pipes, and connecting a pump to the header.

The invention also contemplates a method of installing a well pointwhich comprises applying a sleeve in closely fitting relation with thelower portion of a well point pipe having an open bottom and straineropenings through the side of said lower portion so that said sleevecloses said openings, said sleeve being substantially insoluble in waterover a normal operating temperature range and being highly soluble inwater over a temperature range substantially higher than said normalrange, sinking said pipe to a desired depth in the ground while jettingwater downwardly through said pipe at a temperature in said normal rangeleaving said sleeve intact, and passing water into the thus sunk pipe ata temperature in said higher range for a time sufficient to dissolvesaid sleeve. While the use of the sleeve with the stated watersolubility characteristics is particularly advantageous in combinationwith the described drilling of a noncircular pipe, such use is notnecessarily so restricted.

The invention having been generally described, a preferred specificembodiment will now be set forth in detail with reference to theaccompanying drawings in which:

FIGURE 1 is a perspective view of a well point system il installedaccording to the invention with a portion of the surrounding ground areashown in section;

FIGURE 2 is a side elevation view of a well point being installed in theground and an apparatus for installing it;

FIGURE 3 is an enlarged top plan view of the rotary table of theapparatus of FGURE 2 showing the manner in which one of the noncircularpipes is slidingly and drivingly engaged in the corresponding pipereceiving opening of the rotary table;

FIGURE 4 is a fragmentary view, partially in section showing the bottomof a well point with a strainer sealing sleeve used during installation;

FIGURE 5 is a horizontal section taken along the line 5 5 of FlGURE 4;and

FIGURE 6 is a horizontal section corresponding to FIGURE 5 showing amodified form of sleeve.

illustrated in FIGURE l of the drawings is a well point system 11installed in the soil 12 adjacent an excavation 13. The well pointsystem 11 is generally comprised of a plurality of well points 14connected by a header 15 which, in turn, is connected to a suction orvacuum pump 16.

The well points 1d may be sunk into the ground adjacent a constructionproject such as an excavation to a predetermined depth and remain thereso as to enable the ground water to be drained in the area surroundingthe excavation. The well points 14 are connected to the header 15 byintake connections 17. The suction or vacuum pump 16, which may be ofany suitable type, is connected to the header 15 by intake connection 18while the discharge side of the pump may be connected to a dischargeline leading to a storage area or other suitable place of waterdisposal.

Although the well points 14 are shown in the drawings as all being sunkto approximately the same depth, it will be understood that they may besunk to different depths if necessary. The well points of the system arepreferably spaced from three to nine feet apart, depending upon theamount of water contained in the soil and the characteristics of theparticular soil. However, the well points must not be sunk into theground to a depth greater than the range of the pumps suction.

Each of the well points is generally comprised of a noncircular pipehaving a lower Huid inlet end and an upper outlet end. Each of the pipes20 is provided on its extreme lower inlet end with cutting teeth 21.Immediately above the cutting teeth, the lower inlet end of the pipe isprovided with a screened portion having a plurality of openings 22through the side of the pipe for the intake of water from thesurrounding soil after the well point has been installed. The screenopenings exclude earth and rocks, it being understood that some tinesolids inevitably are admitted.

A drilling rig having mostly conventional components may be used toinstall the well points 14. Shown in FIG- URE 2 of the drawings is avehicle 23 having a power driven winch 24 and a derrick or tower 2Smounted on its rear end. During installation of the well points 14, thepipe 2t) is supported at its upper end by a conventional swivel assembly26 which permits the pipe to be rotated while still permitting water topass therethrough. The swivel connection in turn is supported by apower-operated cable 28 wound on the winch 24. The cable 28 has one endconnected to the top of the swivel 26. The cable then extends upwardlyover a pulley 29 hanging from the top of the derrick 25. The cable thenextends down and around the winch 2d, up over a sheave 30 in the swivelassembly and then down to an anchor 31 at the rear of the vehicle 23.Operation of the winch 24 thus applies a downward force to the pipe 20to drive it into the ground.

Water or other drilling iluid may be supplied to the swivel assembly 26and downwardly through the pipe 20 by a exible hose 32 leading from awater connection on the vehicle 23.

Rotative force is applied to the pipe 14 by a power driven rotary table33. In the particular form of the rotary table shown in FIGURE 3, thepower is transmitted through gears 34 and 35. Both the winch 24 and therotary table 33 may be driven by a motor 37. The rotary table isprovided with a noncircular opening 36 which corresponds in shape to andis slightly larger than the pipe 2% to receive the pipe in slidingdriving relation. Preferably the opening 36 and the cross section of thepipe 2@ are square. In operation of the rotary table the pipe 2i? isloosely or slidingly received within the opening 36 so that a slidabledriving engagement is effected. In this manner, a downward force may beapplied to the pipe while at the same time a rotative force is appliedto the pipe by the rotary table to drill the pipe into the ground to apredetermined depth. Although in the preferred embodiment the pipe 2?and the corresponding opening 36 are square in cross section, it will beunderstood that any suitable noncircular configuration may be employed.For example, the cross section of the pipe and the table opening may bea triangle, hexagon, or other polygon, an ellipse or other noncircularclosed curve. The cooperating noncircular configuration of the pipe 29and the opening 36 thus permits a rotative force to be applied to thepipe while simultaneously permitting it to slide through the opening asthe pipe is driven and jetted into the ground.

The use of a square pipe is particularly advantageous in that thecorners of the pipe, as the pipe is rotated, readily cut a holesurrounding the pipe which is larger than the pipe itself. The enlargedhole reduces the frictional resistance of the soil to the sinking of thepipe. It also permits coarse material in the soil to settle to thebottom of the hole adjacent the tip of the well point. The enlarged holealso acts as a reservoir which is convenient for collecting the waterfrom the surrounding soil so that it may be easily exhausted by the wellpoint system.

As previously explained each of the well points of the present inventionis provided on its extreme lower inlet end with a cutting tool. Afterthe well point has been installed in the soil, the tip of the pipe, orthe portion containing the cutting tool, may be obstructed by anysuitable device or material applied below the screen openings 22. Theobstruction can be, but need not be, a complete seal. It is normallysufficient if earth is excluded but water is admitted as by lling thebottom of the pipe with a porous material. Alternatively even water maybe excluded as by grouting concrete into the end of the pipe below thescreen after the latter has been sunk to the desired depth. Thus waterwould be admitted only through the screen openings 22.

After all of the well points 14 are in place, the header 15 is connectedto them and then the pump 16 is attached to the header.

The method of the present invention is advantageous in that it iscapable of quickly and easily installing a well point system through asimultaneous combination of jetting, driving and drilling. In this way,the system may be installed in most types of soil commonly encountered.It is not necessary to tightly grip the Well point pipes in order todrill them into the ground. Thus, the pipe may easily slide through thedriving means. Further, the weakening of the pipes normally occasionedby the cuts or disfigurations resulting from their being tightly grippedis avoided.

An important aspect of the invention is the use of a sealing sleeves 41in each pipe 20 during the installation of each well point 14. Thesleeve is installed in the pipe prior to the start of the sinkingoperation. As shown in FIGURES 4 and 5 the sleeve 41 is mounted inclosely fitting frictional relation to the square pipe 20 to seal theopenings 22 over the length of the screen yarea. Thus mounted the sleeve41 will not move axially in the pipe during the pipe sinking operation.

An important Iphysical characteristic of the sleeve 41 is its watersolubility properties. The sleeve may be of any of several commerciallyavailable materials having the property of being substantially insolublein water over the time period required for a drilling operation at onerange of water temperatures and highly soluble in water over asubstantially higher range of water temperatures. Preferably the sleeveis substantially water insoluble at temperatures below about 100 F. andhighly soluble in water having a temperature higher than about 150 F.

A readily available material having the desired w-ater solubilitycharacteristics is a specially prepared polyvinyl alcohol. In accordancewith one method the water solubility characteristics may be imputed tothe polyvinyl alcohol depending upon the hydroxyl content of thepolymer. Products containing from 70 to 85% of the original acetategroups are insoluble in water, but dissolve in aromatic hydrocarbons andaliphatic esters. When the residual acetate radicals are reduced toabout 35%, solubility in organic solvents disappears and the productdissolves in cold water but precipitates on heating. At somewhat loweracetate content, the resin is soluble in both hot and cold water. Whenalcoholysis is as complete as possible so that only about ive percent orless of the acetate groups remain, the product is substantiallyinsoluble in cold water but dissolves in hot water. The foregoing is onetechnique by which a polyvinyl alcohol material suitable for use in thepresent invention can be made. However, the method of making thematerial is no part of this invention. Suitable materials are availablewhich might be made by other methods. Suitable polyvinyl alcoholmaterials are manufactured, for example, by the Reynolds Metals Company.

Neither the particular composition of the polyvinyl alcohol sleeve northe method of making it form any part of the present invention. Anycommercially available material having the desired water solubilitycharacteristics may be employed. Such material should also have therequisite degree of toughness and strength to remain in place andprovide a seal during the entire drilling operation.

With the sleeve 41 in place the drilling operation proceeds and water isjetted through the pipe I.at a temperature in the normal operating rangesuch that it does not dissolve the sleeve 41. At the conclusion of thedrilling operation, either before or after a concrete grout or otherobstruction is emplaced in the end of the pipe 20, the sleeve 4I isremoved by pumping hot Water having a temperature which causes thesleeve to dissolve. The pumping of the hot water continues for a timeperiod requisite to effect complete dissolution of the sleeve.

It will be understood that usually the drilling operation will beaccomplished using water in the normal ambient temeprature range of say60 to 100 F. Moreover, it is convenient to use hot water in the range ofsay 150 to 212 F. to dissolve the polyvinyl acetate. Preferably,therefore, the water solubility characteristics of the polyvinyl alcoholare such that it is substantially insoluble in the range of 60 to 100 F.and highly soluble in water at a temperature from 150 to 212 F. It willbe understood that the temperature ranges for water insolubility andsolubility, respectively, may be varied. The magnitude of these rangesis not particularly important. The critical requirement is relativeinsolubility at a low temperature range and high solubility at a hightemperature range. Drilling is then accomplished using water in the lowtemperature range and the sleeve dissolution step is accomplished usingwater in the higher temperature range.

Illustrated in FIGURE 6 is a sleeve 42 which may be mounted outsiderather than inside of the pipe 20. In other respects the sleeve 42 isidentical, particularly in its water solubility characteristics, withthe sleeve 41. Since the sleeve is subjected to a high degree ofabrasion when mounted outside of the pipe, it is preferred to place thesleeve inside.

Although the present invention has been illustrated and described withreference to a preferred specific embodi- Iment, it will be understoodthat various modifications may be made by persons skilled in the artwithout departing from the scope of the invention which is definedsolely by the appended claims.

I claim:

1. A method of installing a well point system which comprises providinga plurality of well point pipes having upper and lower portions ofuniform, noncircular cross sections, said pipes having open bottoms withside openings near said bottoms, sinking the lower portions of saidpipes to a desired depth into the ground at spaced locations by,

simultaneously slidingly and drivingly engaging each of the pipes in arotary drilling table having a noncircular pipe receiving opening toreceive the noncircular pipe in driving relation and rotating the rotarytable with the noncircular lower portion of the pipe extending into theground to rotate said lower portion in the ground,

applying a downward force to each of the pipes, and

jetting water downwardly through each of the pipes while it beingrotated,

thereafter obstructing said open bottoms below said side openingsagainst admission of earth,

connecting a header to each of the installed pipes, and

connecting a pump to the header.

2. The method according to claim 1 wherein each of said well point pipecross sections and said rotary table openings are square.

3. The -method according to claim 1 wherein a sleeve is positioned inclosely fitting relation with each of said pipes to close said sideopenings prior t-o the sinking of said pipes, said sleeve beingsubstantially insoluble in water over a normal operating range oftemperatures and being highly soluble in water over a temperature rangesubstantially higher than said normal range, said jetting beingperformed using water at a temperature in said normal operating range,and including the further step of passing water at a temperature in saidhigher range into the installed pipes for a time sufficient to dissolvesaid s eeve.

' 4. The method according to claim 3 wherein said sleeve 1s positionedinside of said pipe.

5. A method of installing a well point which comprises applying a sleevein closely fitting relation with the lower portion of a well point pipehaving an open bottom and strainer openings through the side of saidlower portion so that said sleeve closes said openings,

said sleeve being substantially insoluble in Water over a normaloperating temperature range and being highly soluble in water over atemperature range substantially higher than said normal range,

sinking said pipe to a desired depth in the ground while jetting waterdownwardly through said pipe at a temperature in said normal rangeleaving said sleeve intact, and

passing water into the thus sunk pipe at a temperature in said higherrange for a time suicient to dissolve said sleeve.

6. The method according -to claim 5 further comprising the step ofobstructing the bottom of said pipe below said strainer openings againstthe admission of earth after said pipe is sunk to said desired depth.

7. The method according to claim 6 wherein concrete is grouted into saidpipe below said side openings to seal the lower end of the pipe aftersaid pipe is sunk to said desired depth.

8. The method according to claim 6 wherein said insoluble temperaturerange is below F. and said soluble temperature range is above F.

9. The method according to claim 6 wherein said sleeve is made ofpolyvinyl alcohol having said water solubility characteristics.

10. 'Ihe method according to claim 9 wherein said -insoluble temperaturerange is below 100 E. and said soluble temperature range is above 150 F.

11. The method according to claim 6 wherein said pipe has a uniformnoncircular cross section and is rotated during said sinking operationby la rotary table having a noncircular opening to slidably receive saidpipe `in driving relation.

12. The method according to claim 11 wherein said pipe cross section andsaid rotary table opening are square.

References Cited UNITED STATES PATENTS 1,521,809 1/1925 Green 166-2271,688,356 10/1928 Romney 175-314 2,226,804 12/ 1940 Carroll 166-2272,835,328 5/1958 Thompson 175-314 3,169,586 2/1965 Bullard 175-3203,215,213 11/1965 Morimoto 175-314 10 ERNEST R. PURSER, PrimaryExaminer.

NILE C. BYERS, JR., Examiner.

